Amplifier for sound-reproducing machines



.I. w. BOOTH.

I AH LHIER FQKSOUND BEPRODUCING MACHINES.

APPUCAHON FILED "AR- 22, 1920- 1,376,508. Patented May 3, 1921.

2 SHEETS-SHEET I.

Jim/rm? Jaw/v uzuam.

J. W. BOOTH.

AMPEIFIER FOR SOUND REPRODUCING MACHiNES.

APPLICATION FILED MAR. 22. 1920.

1,376,508- fiiiiilizfi I a g 51 I I p I l l' 63 .56 52 05 a0 J5 JAE/mm) .m/m/ M30477.

UNITED STATES PATE T owl mrmrmn FOR sounnnnrnonncniemacmnns.

Specification of Letters Patent.

Patented May a, 1921.

Application filed March 22, 1920. Serial 1%. 367,920.

To all whom it may concern.

Be it known that 1, JOHN W. BOOTH, a citizen of the United States of America, and resident of the townof Trenton, in the county of Hastings, Province of Ontario, Dominion of Canada, have invented certain new and useful Improvements in Amplifiers for Sound-Reproducing Machines, of which the following is a specification;

' This invention relates to improvements in amplifiers for sound reproducing machines, and the objects of the invention are to attain mellowness, sweetness and clearness of tone, combined with good volume.

Further objects are to provide such an amplifier which will enable the tone to be reinforced in a natural and satisfactorymanner, and without obstruction of the her mony 1n theoriglnal tone.

More specific objects are generally to improve and simplify the construction of the amplifier to better adapt the several parts to perform the functions required of'them. It consists essentially of the improved construction, hereinafter described in detail in the accompanying specification and drawings:

In the drawings:

Figure 1 is a perspective view of the am- Fig. 2 is a cross sectional view.

Fig. 3 is an inverted plan of the underside of the sound box. F ig; 4 is a'longitudinal section of an alternative form of the invention. Fig. 5 is across section of the alternative form on the line tic-00 of,

Fig. 4.

Inthe drawings, like characters of reference indicate corresponding parts in all the figures Referring to the drawings, it will be seen that thevamplifier consists of two main or essential members namel a sound box A and an amplifying mem er B, the amplif ing member being formed with a gradua ly enlarged tone passage 10, which leads from the tone passage (not shown) to one end of the mouth 11 of the offset end.

It will be understood that the amplifier may be used in connection with any well known form of sound reproducing machine.

made in suitable size and 'form and fitted to the machine to which it is used,,the inner end of the passage 10 being connectedto the .tone passage from the tone 31:111.? g

the tone arm and tone regulated if desired by a suitable gate valve 12 including a sliding gate 13 operating in a suitable housing 14. The amplifying member B is formed with an upper wa l 15 and a lower wall 16, the lower Wall at one point having openings 17 preferably circular therein which connects with the sound hole 18 in the sound box A.

The resonance box A includes upper and lower walls 19 and 20 and suitable side walls 21. The front edge of the walls 16 of the amplifying member is raised and is secured to the resonance box. From the front to the rear the .amplifying-member B is tapered centrally, and the "center portion. at the rear is supported on the sound box A.

' At the extreme rearthe amplifying member B is raised a short distance one-eighth thinner than the lower wall.

23 indicates vibrating bars of which four extend diagonally from the sound hole 18 to the corners of the resonance box the underside of the wall 19.

2 1 indicates-a sound post connecting the walls 19 and 20 to the resonance box A ad- 'acent to the sound hole 18; The vibrating are 23 extend to within a short distance of the side walls 21. I I

It will be seen that the sound post 24 will cause the upper and lower walls 19 and 20 to vibrate in unison and thereby control and strengthen the tone of the complete instrument. I r It will be seen further that the construction above described enables the amplifier to correspond with the instrumenthused in violin construction, thus for instance, the record on the sound reproducing machine which vibrates the needle bar would correspond to .the violin how; the resonance box,

passagewould correspond to the strings oft e violin j the contact at the "rear of the amplifier to the tail off the bridge of the violin; the sound holes 17 and 18 to the holes of a violin; the contact at the front of the member 1% to the neck of the violin; the sound post 24: to correspand to the sound post of the violin, while the vibrating bars 23 assist in distributing the vibration and the complete resonance box A will correspond with the body ofthe violin.

In the alternative form of the invention shown in Figs. 4.. and 5, B indicates the resonance box and C theamp'lifier mounted on top of the same having at'one end an inclined deflecting plate D located behind the sound hole 30 and below the opening of the sound passage 31 in the sound conducting member E, which leads from the tone arm to the sound reproducing machine.

A suitable sound post 32 is provided and sound box B and amplifier connected to the resonance box at opposite ends 33 and 34 and around the sound hole 30 at 35, suitable spacing plates or bars are provided at these points.

This part of the invention may be as in the previous form provided with radially extending sound vibrating bars 36.

i It is found that with the amplifier constructed in this manner it is'possible to obtam mellowness, sweetness and clearness, and

above .all plainnes's combined with good volume.

The amplifier is felt or rubber cushions, insulated entirely from the cabinet or other machine, whereby they Will have free and undisturbed vibrapreferably supported on 1,376,508. w I v tion and not be permanently attached to the sound reproducing machine.

The various parts of the device are preterably constructed of thin and well seasoned wood.

As many changes could beinadein the above construction, and many apparently widely different embodiments of my invention within the scope of the claim, constructed without departing from the spirit or scope thereof, it is intended that all mattercontained in the accompanying specification and drawings shall be interpreted as illustrative and not in a limiting sense. 'hat I claim as my invention is An amplifier for sound reproducing machines comprising a resonance box having a sound hole therein, an ampli'iyingmember with gradually enlarged sound passageways provided with a corresponding sound hole registering with the said sound hole,the said amplifier being connected to the resonance box at three points, namely, at the front, at the rear, and adjacent to the sound. hole, an

annular flange connecting the said sound holes, a sound post in the resonance box ada 

